Object detecting method and non-transitory computer-readable recording medium storing an object detection program

ABSTRACT

An object detecting method includes dividing a standard pattern into two or more areas radially from a central point; selecting, in each divided area of the standard pattern, a standard pattern pixel position at the maximum distance from the area dividing central point as a standard pattern representative point; dividing a determined pattern into two or more areas; selecting, in each divided area of the determine pattern, a determined pattern pixel position at the maximum distance from the area dividing central point as a determined pattern representative point; determining a positional difference between the standard pattern representative point and the determined pattern representative point in the corresponding divided areas; and determining the determined pattern as a target object when the positional differences in all of the divided areas are within a predetermined range.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an object detecting method fordetecting a target object in an image, and a non-transitorycomputer-readable recording medium storing a program for causing acomputer to perform an object detecting method.

2. Description of the Related Art

Technologies for detecting an object in an image taken by a camera,e.g., by processing information of the image, are being utilized invarious fields of industry. For example, in the field of industrialrobots, the information of an image imaged by a camera may be processedto detect an object in the image, and determine a positional error ofthe object in order to correct the position of an industrial robot. Inthe field of semiconductor manufacturing, in a size measuring step usinglength-measurement SEM (scanning electron microscopy) technology, anarea around an alignment mark formed on a wafer may be taken by acamera, and the information of the image may be processed to detect theposition of the alignment mark so that a position error of the wafer canbe corrected.

Such image processing for object detection may involve pattern matching.For example, Japanese Laid-open Patent Publication No. 2008-234261discusses a pattern matching technology whereby an image of an object isregistered in advance, and an image including the object is obtainedduring an actual operation. Correlation values between the registeredimage and the image taken during the actual operation are calculated,and the presence or absence of the object or its position is detectedbased on the correlation values.

Pattern matching for object detection may involve moving apre-registered standard pattern of a target object over an actual imageincluding a determined pattern, and detecting a position in the imagewhere the correspondence between the standard pattern and the determinedpattern is large. Such an object detecting method based on patternmatching may involve the handling of large amounts of information andtake a long time for object detection.

SUMMARY OF THE INVENTION

In one aspect, an object detecting method includes dividing an area of astandard pattern into two or more areas radially from an area dividingcentral point; selecting, in each of the divided areas of the standardpattern, a standard pattern pixel position at the maximum distance fromthe area dividing central point as a standard pattern representativepoint; dividing an area of a determined pattern into two or more areasunder the same condition as in the step of selecting the standardpattern representative point and with reference to the area dividingcentral point; selecting, in each of the divided areas of the determinepattern, a determined pattern pixel position at the maximum distancefrom the area dividing central point as a determined patternrepresentative point; determining a positional difference between thecoordinates of the standard pattern representative point and thecoordinates of the determined pattern representative point in thecorresponding divided areas; and determining the determined pattern as atarget object when the positional differences in all of the dividedareas are within a predetermined range.

In another aspect, a non-transitory computer-readable recording mediumstores a program that causes a computer to perform the object detectingmethod.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method of detecting a target object accordingto an embodiment of the present invention;

FIG. 2 illustrates a standard pattern;

FIG. 3 illustrates an area dividing central point and lines for dividingan area of the standard pattern into eight parts;

FIG. 4 illustrates representative points of the standard pattern;

FIG. 5 illustrates a determined pattern image taken of an area around analignment mark on a wafer, the image showing two determined patterns;

FIG. 6 illustrates an area dividing central point and lines for dividingan area of a first determined pattern into eight parts, andrepresentative points of the first determined pattern;

FIG. 7 illustrates an area dividing central point and lines for dividingan area of a second determined pattern into eight parts, andrepresentative points of the second determined pattern;

FIG. 8 illustrates a determined pattern image including two roundeddetermined patterns;

FIG. 9 illustrates an area dividing central point and lines for dividingan area of a first round determined pattern into eight parts, andrepresentative points of the first determined pattern;

FIG. 10 illustrates an area dividing central point and lines fordividing an area of a second round determined pattern, andrepresentative points of the second determined pattern;

FIG. 11 illustrates another example of the standard pattern, an areadividing central point and lines for dividing an area of the standardpattern into four parts, and representative points of the standardpattern;

FIG. 12 illustrates another example of the standard pattern, an areadividing central point and lines for dividing an area of the standardpattern into eight parts, and representative points of the standardpattern, where some of the divided areas do not have the representativepoints;

FIG. 13 illustrates a result of an edge detection process performed onthe standard pattern of FIG. 3;

FIG. 14 illustrates an area dividing central point and lines fordividing an area of an outline portion of the standard pattern of FIG.13 into eight parts, and representative points of the standard pattern;

FIG. 15 illustrates another example of the standard pattern, an areadividing central point and lines for dividing an area of an outlineportion of the standard pattern into eight parts, and representativepoints of the standard pattern; and

FIG. 16 illustrates a computer and a non-transitory computer-readablerecording medium that stores a program that causes the computer toperform an object detecting method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention is described with reference to anexample where an alignment mark used for wafer position error correctionis detected as a target object during a size measuring step using alength-measurement SEM in a semiconductor device manufacturing process.In the size measuring step, when the wafer is transported to an XY stageof a length-measurement SEM apparatus, a small wafer position error maybe caused. Such a positional error is corrected with reference to thealignment mark. Because the wafer is positioned with reference to acut-out which may be referred to as an “orientation flat” or a “notch”,the positional error of the wafer during the transport to the XY stagemay typically consist of displacements in the X or Y directions, withlittle error in a rotational direction.

FIG. 1 is a flowchart of a method of detecting the alignment mark as thetarget object according to the present embodiment. FIG. 2 illustrates astandard pattern. FIG. 3 illustrates an area dividing central point andlines for dividing an area of the standard pattern into eight parts.FIG. 4 illustrates standard pattern representative points. FIG. 5illustrates a determined pattern image showing two determined patterns.FIG. 6 illustrates an area dividing central point and lines for dividingan area of a first determined pattern into eight parts. FIG. 6 alsoillustrates representative points of the first determined pattern. FIG.7 illustrates an area dividing central point and lines for dividing anarea of a second determined pattern into eight parts. FIG. 7 alsoillustrates second determined pattern representative points.

With reference to FIG. 1, in step S1, information of a standard patternimage including a standard pattern of the alignment mark is read. Instep S2, a binarizing process is performed on the standard pattern imageto extract the standard pattern of the alignment mark. The binarizingprocess may include converting the brightness of pixels into black andwhite values based on predetermined reference values. FIG. 2 illustratesthe area of a standard pattern 1 extracted after the binarizing process.

In step S3, an area dividing central point G1 is set for dividing thearea of the standard pattern 1 extracted in step S2. In accordance withthe present embodiment, the area dividing central point G1 correspondsto the geometric center of the standard pattern 1. In FIG. 3, the areadividing central point G1 (geometric center) of the area of the standardpattern 1 is indicated by a black dot. In FIG. 3, the area of thestandard pattern 1, which is shown solid black in FIG. 2, is indicatedby a dot pattern so that the area dividing central point G1 can beclearly seen.

In step S4, the area of the standard pattern 1 is radially divided fromthe area dividing central point G1. The area of the standard pattern 1may be divided into eight divided areas A1-1 through A1-8 by four linespassing through the area dividing central point G1, as illustrated inFIG. 3.

In step S5, in each of the divided areas A1-1 through A1-8, pixels ofthe standard pattern 1 that are located at the maximum distances fromthe area dividing central point G1 may be determined as standard patternrepresentative points T1-1 through T1-8. For example, the positions ofthe pixels corresponding to the standard pattern representative pointsT1-1 through T1-8 are indicated by white dots in FIG. 4.

In step S6, position information of the pixels corresponding to thestandard pattern representative points T1-1 through T1-8 is stored asrepresentative point information. In accordance with the presentembodiment, coordinates information of the representative points isstored, assuming XY coordinates with the area dividing central point G1as the origin. Alternatively, the coordinates information of thestandard pattern representative points may be stored by assuming XYcoordinates with a point other than the area dividing central point asthe origin. Further alternatively, instead of assuming the XYcoordinates, the coordinates information of the standard patternrepresentative points may be stored by assuming polar coordinates withthe area dividing central point or another point as the origin (pole).

In step S7, information of a determined pattern image of an area aroundthe alignment mark on the wafer is read. In step S8, a binarizingprocess and a labeling process are performed on the determined patternimage to extract a determined pattern. While in step S1 the informationof the standard pattern image that is read includes only the standardpattern 1 of the alignment mark, the determined pattern image that isread in step S8 includes an area around the alignment mark. Thus, thedetermined pattern image may include pattern information of items orshapes other than the target object (alignment mark). For example, thedetermined pattern image 4 illustrated in FIG. 5 includes a firstdetermined pattern 2 and a second determined pattern 3. The labelingprocess may involve adding a group attribute to each pixel and may bevery effective in identifying an area of each of plural patterns in animage.

In step S9, a first determined pattern is selected. In accordance withthe present embodiment, the first determined pattern 2 is selected. Thefollowing steps S10 through S14 are performed for each determinedpattern extracted in step S8.

In step S10, the area dividing central point G2 for dividing the area ofthe first determined pattern 2 is set. Because the geometric center ofthe standard pattern 1 has been set in step S3 as the area dividingcentral point G1, the geometric center of the first determined pattern 2is set as the area dividing central point G2 in step S10. The areadividing central point G2 of the first determined pattern 2 is indicatedby a black dot in FIG. 6. In FIG. 6, the areas of the first determinedpattern 2 and the second determined pattern 3, which are shown solidblack in FIG. 5, are indicated by dot patterns in FIG. 6 so that thearea dividing central point G2 can be clearly seen.

In step S11, the area of the first determined pattern 2 is radiallydivided from the area dividing central point G2. As illustrated in FIG.6, the area of the first determined pattern 2 is divided into eightdivided areas A2-1 through A2-8 by four lines passing through the areadividing central point G2, in the same way that the area of the standardpattern 1 is divided in step S4.

In step S12, in each of the divided areas A2-1 through A2-8, pixels ofthe first determined pattern 2 that are located at the maximum distancesfrom the area dividing central point G2 are determined as the firstdetermined pattern representative points T2-1 through T2-8. In FIG. 6,the positions of the pixels corresponding to the first determinedpattern representative points T2-1 through T2-8 are indicated by whitedots.

In step S13, a positional difference between the coordinates of thestandard pattern representative points T1-1 through T1-8 and thecoordinates of the first determined pattern representative points T2-1through T2-8 are determined for each corresponding divided area. Thecoordinates of the first determined pattern representative points T2-1through T2-8 may be determined with reference to the origin of thecoordinates of the standard pattern representative points T1-1 throughT1-8 registered in step S6. For example, when the coordinatesinformation of the standard pattern representative points T1-1 throughT1-8 is registered by assuming the XY coordinates with the area dividingcentral point G1 as the origin, the coordinates of the first determinedpattern representative points T2-1 through T2-8 may be determined byassuming XY coordinates with the area dividing central point G2 as theorigin. Then, the positional difference between the standard patternrepresentative points and the first determined pattern representativepoints may be determined for each corresponding divided area.

In step S14, it is determined whether the first determined pattern 2 isthe target object. Specifically, it is determined whether the positionaldifferences are within a predetermined range in all of the dividedareas. The “predetermined range” may correspond to an area of 10 pixels.With reference to FIGS. 4 and 6, the positions of the standard patternrepresentative points T1-1 through T1-8 with respect to the areadividing central point G1 are clearly different from the positions ofthe first determined pattern representative points T2-1 through T2-8with respect to the area dividing central point G2 in all of the dividedareas. Thus, the positional differences between the standard patternrepresentative points and the first determined pattern representativepoints may not be within the predetermined range. Thus, it may bedetermined that the first determined pattern 2 is not the target object(alignment mark) (“No” in step S14).

In step S15, it is determined whether there is a determined pattern yetto be processed. Because the second determined pattern 3 is notprocessed yet (“Yes”), the routine proceeds to step S16. When there isno determined pattern to be processed (“No”), the process ends. In stepS16, the next determined pattern is selected. For example, the seconddetermined pattern 3 is selected, and then the routine returns to stepS10.

In step S10, an area dividing central point G3 for dividing the area ofthe selected second determined pattern 3 is set. Here again, thegeometric center of the second determined pattern 3 may be set as thearea dividing central point G3. In FIG. 7, the area dividing centralpoint G3 of the second determined pattern 3 is indicated by a black dot.The areas of the first determined pattern 2 and the second determinedpattern 3, which are shown solid black in FIG. 5, are indicated by dotpatterns in FIG. 7 so that the area dividing central point G3 can beclearly seen.

In step S11, the area of the second determined pattern 3 is radiallydivided from the area dividing central point G3. For example, the areaof the second determined pattern 3 is divided into eight divided areasA3-1 through A3-8 by four lines passing through the area dividingcentral point G3, as illustrated in FIG. 7, in the same way that thearea of the standard pattern 1 is divided in step S4.

In step S12, in each of the divided areas A3-1 through A3-8, pixels ofthe second determined pattern 3 that are located at the maximumdistances from the area dividing central point G3 are determined as thesecond determined pattern representative points T3-1 through T3-8. InFIG. 7, the positions of the pixels corresponding to the seconddetermined pattern representative points T3-1 through T3-8 are indicatedby white dots.

In step S13, a positional difference between the coordinates of thestandard pattern representative points T1-1 through T1-8 and those ofthe second determined pattern representative points T3-1 through T3-8 isdetermined for each corresponding divided area. The coordinates of thesecond determined pattern representative points T3-1 through T3-8 may bedetermined with reference to the origin of the coordinates of thestandard pattern representative points T1-1 through T1-8 registered instep S6. Then, the positional differences between the standard patternrepresentative points and the second determined pattern representativepoints may be determined for each corresponding divided area.

In step S14, it is determined whether the second determined pattern 3 isthe target object. With reference to FIGS. 4 and 7, the positions of thestandard pattern representative points T1-1 through T1-8 with referenceto the area dividing central point G1 are the same or substantially thesame as the positions of the second determined pattern representativepoints T3-1 through T3-8 with reference to the area dividing centralpoint G3 in all of the divided areas. Thus, the positional differencesbetween the standard pattern representative points and the seconddetermined pattern representative points may be within a predeterminedrange. In this case, it may be determined that the second determinedpattern 3 is the target object (alignment mark) (“Yes”), and the processmay be terminated.

In accordance with the present embodiment, because it is determinedwhether the determined pattern is the target object standard pattern byusing the representative points T1-1 through T1-8 and the determinedpattern representative points T2-1 through T2-8 and T3-1 through T3-8,the amount of information that is processed is less than that ofrelated-art pattern matching methods. Thus, the target object can bedetected at high speed.

Further, because the information of the previously registered standardpattern is that of the standard pattern representative points T1-1through T1-8, the amount of information that is registered is less thanin the case where the information of the entire standard pattern isregistered.

In accordance with the present embodiment, the determination process isfirst performed for the first determined pattern 2 of the determinedpatterns 2 and 3. However, the order of the determination process in thecase of plural determined patterns is not particularly limited. Forexample, the determination process may be performed for the seconddetermined pattern 3 first. In this case, the process may end upondetermination that the second determined pattern 3 is the target object(alignment mark) (“Yes” in step S14), and no further determinationprocess may be performed for the first determined pattern 2. However,even upon determination that any of plural determined patterns is thetarget object, the determination process may be continued for one ormore remaining un-processed determined patterns. In this case, when itis determined that plural determined patterns correspond to the targetobject and when it is preferable to select only one of the determinedpatterns as the target object, the determined pattern having thesmallest total value of the positional differences may be selected asthe target object.

In accordance with the present embodiment, if the target object cannotbe obtained after performing the process of steps S10 through S14 forone selected determined pattern, then the same process may be performedfor the next determined pattern. Preferably, after the determinedpattern representative points are determined for each of pluraldetermined patterns, the target object determination step may beperformed for each of the determined patterns.

Preferably, when it is possible that the magnification ratio of theimages may vary due to different distances between the camera and theimaged object, for example, the determined pattern representative pointinformation may be corrected after the determined pattern representativepoints are selected in step S12, and then the positional differences maybe calculated in step S13.

In a specific method of correcting the representative point information,the coordinates information of the determined pattern representativepoints T2-1 through T2-8 or T3-1 through T3-8 may be corrected asfollows. For example, the magnification ratio of the area of the firstdetermined pattern 2 is varied such that the distance between thestandard pattern representative point T1-1 and the area dividing centralpoint G1 in FIG. 4 is equal to the distance between the first determinedpattern representative point T2-1 corresponding to the standard patternrepresentative point T1-1 and the divided area central point G2 in thefirst determined pattern 2 (FIG. 6). Also, the magnification ratio ofthe area of the second determined pattern 3 may be varied such that thedistance between the standard pattern representative point T1-1 and thearea dividing central point G1 illustrated in FIG. 4 is equal to thedistance between the second determined pattern representative point T3-1corresponding to the standard pattern representative point T1-1 and thedivided area central point G3 in the area of the second determinedpattern 3 (FIG. 7).

Preferably, after varying the magnification ratio for correcting thecoordinates positions of the determined pattern representative points,if, with respect to the X coordinate or the Y coordinate, the differencebetween the minimum coordinate value and the maximum coordinate value ofthe standard pattern and the difference between the minimum coordinatevalue and the maximum coordinate value of the determined pattern areequal to or more than a predetermined value, such as 10 pixels, thedetermination process of step S14 may be omitted for the particulardetermined pattern.

The alignment mark or other patterns formed in the photoengraving stepor etching step of a semiconductor device manufacturing process may berounded, as illustrated in FIG. 8. In such a case, in the case of analignment mark, for example, it may not be possible to detect adetermined pattern that is completely identical in terms of coordinatesof the representative points of a pre-registered standard pattern. Inaccordance with the present embodiment, as described above, it isdetermined that the determined pattern is the target object when thepositional differences between the coordinates of the standard patternrepresentative points and the coordinates of the determined patternrepresentative points are within the preset range, thus enabling anaccurate detection of even a rounded alignment mark or target pattern.

FIG. 9 illustrates the area dividing central point G2 and lines fordividing the area of a rounded first determined pattern 2 into eightparts, and their first determined pattern representative points T2-1through T2-8. FIG. 10 illustrates the area dividing central point G3 andlines for dividing the area of a rounded second determined pattern 3into eight parts, and their second determined pattern representativepoints T3-1 through T3-8.

As illustrated in FIGS. 9 and 10, even when the determined pattern 2 or3 is rounded, the second determined pattern representative points T3-1through T3-8 may be obtained substantially at the same positions as thestandard pattern representative points T1-1 through T1-8 illustrated inFIG. 4. Thus, the second determined pattern 3 may be determined as thetarget object (alignment mark).

In the foregoing embodiment, the area of the standard pattern and thoseof the determined patterns are divided into eight parts. Preferably, thenumber of the divided areas or their positions may be determineddepending on the pattern shape of the detected object. The number of thedivided areas may be two or more. For example, as illustrated in FIG.11, the area of a standard pattern 5 is divided into four divided areasA5-1 through A5-4 with respect to the geometric center of the standardpattern 5 as the area dividing central point G5, thus obtaining fourstandard pattern representative points T5-1 through T5-4.

The representative points may not be selected in one or more of pluraldivided areas. For example, in a case where the area of the standardpattern 5 is divided into eight divided areas A5-1 through A5-8 asillustrated in FIG. 12, no representative points may be selected in thedivided areas A5-2, A5-4, A5-6, and A5-8 while the standard patternrepresentative points T5-1, T5-3, T5-5, and T5-7 are selected in thedivided areas A5-1, A5-3, A5-5, and A5-7.

In the foregoing embodiment, in the process of selecting the standardpattern representative points or the determined pattern representativepoints, the selecting process is performed with regard to all of thepixels of the standard pattern or the determined pattern. Alternatively,similar results may be obtained by performing the representative pointselecting process only with regard to the pixel information of anoutline portion of the standard pattern or the determined pattern. Inthis case, the representative point selecting process may be performedfaster than in the case of performing the representative point selectingprocess with regard to all of the pixels of the standard pattern or thedetermined pattern. An example is described with reference to a standardpattern.

The pixel information of an outline portion of a pattern may be obtainedby a method which may be generally referred to as “edge detection”, bywhich a pattern outline is calculated based on changes in imagebrightness. FIG. 13 illustrates the result of an edge detection processperformed on the standard pattern 1 illustrated in FIG. 2. By performingthe edge detection process on the standard pattern 1, a standard patternoutline portion 1 a is obtained.

FIG. 14 illustrates an area dividing central point G1 a and lines fordividing the area of the standard pattern outline portion 1 a of FIG. 13into eight parts, and their standard pattern representative points. Inthe illustrated example, the area dividing central point G1 acorresponds to the geometric center of the standard pattern outlineportion 1 a. The area of the standard pattern outline portion 1 a isdivided into eight divided areas A1 a-1 through A1 a-8 under the sameconditions (such as the method of setting the area dividing centralpoint and the method of area division) as in the case of area divisiondescribed with reference to FIG. 3. As a result, standard patternrepresentative points T1 a-1 through T1 a-8 are obtained. The positionsof the standard pattern representative points T1 a-1 through T1 a-8 withrespect to the area dividing central point G1 a are the same as thepositions of the standard pattern representative points T1-1 throughT1-8 with respect to the area dividing central point G1 (see FIGS. 4 and14).

Preferably, in the case where the representative point selecting processis performed by using the outline portion of a pattern, pixel positionsat the minimum distances from the area dividing central point may beselected as representative points.

Preferably, the method of determining the representative points may bevaried from one divided area to another. For example, as illustrated inFIG. 15, a standard pattern outline portion 5 a is determined for thestandard pattern 5 illustrated in FIG. 12. The geometric center of thestandard pattern outline portion 5 a is set as the area dividing centralpoint G5 a, and, for the divided areas A5 a-1, A5 a-3, A5 a-5, and A5a-7 among the eight divided areas A5 a-1 through A5 a-8, pixel positionsof the standard pattern outline portion 5 a that are at the maximumdistances from the area dividing central point G5 a are selected as thestandard pattern representative points T5 a-1, T5 a-3, T5 a-5, and T5a-7. With regard to the divided areas A5 a-2, A5 a-4, A5 a-6, and A5a-8, the pixel positions of the standard pattern outline portion 5 athat are at the minimum distances from the area dividing central pointG5 a are selected as the standard pattern representative points T5 a-2,T5 a-4, T5 a-6, and T5 a-8, respectively.

Thus, a divided area in which the pixel coordinates of a position at themaximum distance from the area dividing central point are selected as arepresentative point may be present together with a divided area inwhich the pixel coordinates of a position at the minimum distance fromthe area dividing central point are selected as a representative point.

In the foregoing embodiment, the information of the standard patternrepresentative points is obtained by using the image information of thestandard pattern in steps S1 through S5 of the flowchart of FIG. 1.Preferably, the information of the standard pattern representativepoints may be obtained based on design data.

For example, when it is determined in advance that, in the case of thestandard pattern 1 illustrated in FIG. 2, the geometric center of thestandard pattern 1 is set as the area dividing central point (method ofsetting the area dividing central point), and that the area of thestandard pattern 1 is divided into eight divided areas with respect tothe area dividing central point as illustrated in FIG. 3 (method ofsetting the divided areas), an operator may be able to readily selectthe coordinates positions of the standard pattern representative pointsT1-1 through T1-8 (see FIG. 4) of the standard pattern 1, based ondesign data.

The steps of the foregoing embodiment may be realized by executing aprogram that causes a computer to perform the steps. The program may bestored in a non-transitory computer-readable recording medium 200 anddownloaded therefrom into a computer 100, as illustrated in FIG. 16.

Although this invention has been described in detail with reference tocertain embodiments, variations and modifications exist within the scopeand spirit of the invention as described and defined in the followingclaims.

For example, the steps of the foregoing embodiments may be performedwithout drawing the figures with reference to which the foregoingembodiments have been described. While the alignment mark is used as atarget object in the foregoing embodiments, the target object is notlimited to an alignment mark and may include any pattern shape.

The standard pattern may be drawn or imaged. Also, the determinedpattern may be drawn or imaged. An embodiment of the present inventionmay be applied to an operation for detecting a specific pattern shape ina drawn or imaged image, such as a wafer positioning operation during asize-measuring step of a semiconductor manufacturing process.

The determined pattern representative point selecting step may beperformed under the same conditions as in the standard patternrepresentative point selecting step. Specifically, in both of therepresentative point selecting steps, the area dividing central pointmay be set or the area may be divided by the same methods. Thus, for thetwo representative point selecting steps, the coordinates of the areadividing central point may be the same or different.

The standard pattern representative point selecting step and thedetermined pattern representative point selecting step may includesetting a center or the geometric center of a pattern as the areadividing central point. The “center” of the pattern may include a pointwith coordinate values obtained by dividing in half a sum of the maximumvalue and the minimum value of each of the variables of the plural pixelcoordinates (which are pairs of the variables) indicating the positionsof the pixels of the pattern. The “geometric center” of the pattern mayinclude a point with coordinates of an average value of each thevariables of the plural pixel coordinates (which are pairs of thevariables) indicating the positions of the pixels of the pattern.

The standard pattern representative point selecting step and thedetermined pattern representative point selecting step may include notperforming the representative point selecting process in apre-designated first divided area of the divided areas.

The standard pattern representative point selecting step and/or thedetermined pattern representative point selecting step may includeselecting the representative points by using only the pixel informationof an outline portion of the pattern. The pixel information of theoutline portion of the pattern may be determined by an edge extractingprocess. However, this does not exclude the selection of therepresentative points by using the pixel information of the entirety ofthe standard pattern or the determined pattern in the correspondingrepresentative point selecting step.

When the center or the geometric center of the standard pattern or thedetermined pattern is set as the area dividing central point, therepresentative point selecting steps may include determining the areadividing central point by using only the pixel information of theoutline portion of the pattern, or the pixel information of the entirepattern.

In the representative point selecting step in which the representativepoints are selected by using only the pixel information of the outlineportion of the pattern, a pattern pixel position located at the minimumdistance from the area dividing central point may be selected as arepresentative point as regards a pre-designated second divided area ofthe divided areas.

In the object detecting method according to an embodiment, the standardpattern representative point selecting step may include setting astandard pattern pixel position selected in advance based on design dataof a standard pattern as a standard pattern representative point,instead of processing actual image information. When the method ofsetting the area dividing central point and the divided area settingmethod are determined, an operator can easily select the coordinatesposition of the standard pattern representative point selected withreference to the standard pattern based on the design data.

The standard pattern and the determined pattern may include an alignmentmark used for positioning a semiconductor wafer. In accordance with anembodiment, a non-transitory computer-readable recording medium maystore an object detection program configured to cause a computer toperform the steps of the object detecting method.

In the object detecting method according to an embodiment, the objectdetermination step includes determining whether a determined pattern isa target object by using the standard pattern representative pointsobtained in the standard pattern representative point selecting step andthe determined pattern representative points obtained in the determinedpattern representative point selecting step. Thus, the method requiresless information than a related-art pattern matching method, thusenabling a high-speed detection of the target object.

Further, in the object detecting method according to an embodiment, whenthe information corresponding to the standard pattern is registered inadvance, the information of the standard pattern representative pointsmay be registered. Thus, the method of the embodiment requires lessinformation that needs to be registered than in the case of registeringthe information of the entire standard pattern.

In the object detecting method according to an embodiment, the standardpattern representative point selecting step or the determined patternrepresentative point selecting step may include setting the geometriccenter of the pattern as the area dividing central point. In this way,when the steps of the method are performed by a computer, the areadividing central point suitable for the standard pattern or thedetermined pattern may be automatically set without the operator settingthe area dividing central point.

The standard pattern representative point selecting step or thedetermined pattern representative point selecting step may include notperforming the representative point selecting process as regards apre-designated first divided area of the divided areas. In this way, arepresentative point suitable for the standard pattern or the determinedpattern may be selected.

The standard pattern representative point selecting step and/or thedetermined pattern representative point selecting step may includeselecting the representative point by only using the pixel informationof an outline portion of a pattern. In this way, the informationprocessing time can be reduced compared to when the image information ofthe entire pattern is used.

The representative point selecting step in which the representativepoint is selected by using only the pixel information of the outlineportion of the pattern may include selecting a pattern pixel positionlocated at the minimum distance from the area dividing central point asthe representative point as regards a pre-designated second divided areaof the divided areas. In this way, a representative point suitable forthe standard pattern or the determined pattern may be selected.

In the object detecting method according to an embodiment, the standardpattern representative point selecting step may include setting, as thestandard pattern representative point, a standard pattern pixel positionthat is selected based on design data of a standard pattern in advance,instead of processing actual image information. In this way, the timefor the processing of selecting the standard pattern pixel position atthe maximum distance from the area dividing central point as regards thestandard pattern may be omitted.

A non-transitory computer-readable recording medium according to anembodiment stores an object detection program configured to cause acomputer to perform the steps of the object detecting method. Thus, theobject detecting method according to an embodiment may be performed bythe computer.

The present application is based on Japanese Priority Application No.2010-100743 filed Apr. 26, 2010, the entire contents of which are herebyincorporated by reference.

1. An object detecting method comprising: dividing an area of a standard pattern into two or more areas radially from an area dividing central point; selecting, in each of the divided areas of the standard pattern, a standard pattern pixel position at the maximum distance from the area dividing central point as a standard pattern representative point; dividing an area of a determined pattern into two or more areas under the same condition as in the selecting of the standard pattern representative point and with reference to the area dividing central point; selecting, in each of the divided areas of the determined pattern, a determined pattern pixel position at the maximum distance from the area dividing central point as a determined pattern representative point; determining a positional difference between the coordinates of the standard pattern representative points and the coordinates of the determined pattern representative points in the corresponding divided areas; and determining the determined pattern as a target object when the positional differences in all of the divided areas are within a predetermined range.
 2. The object detecting method according to claim 1, wherein each of the selecting of the standard pattern representative point and the selecting of the determined pattern representative point includes setting a center or a geometric center of the corresponding pattern as the area dividing central point.
 3. The object detecting method according to claim 1, wherein each of the selecting of the standard pattern representative point and the selecting of the determined pattern representative point includes not selecting the corresponding representative point in a pre-designated first divided area of the corresponding divided areas.
 4. The object detecting method according to claim 1, wherein the selecting of the standard pattern representative point and/or the selecting of the determined pattern representative point includes selecting the representative point by only using pixel information of an outline portion of the corresponding pattern.
 5. The object detecting method according to claim 4, wherein the selecting of the representative point by using only the pixel information of the outline portion includes selecting a pattern pixel position at the minimum distance from the area dividing central point as the representative point as regards a pre-designated second divided area of the divided areas.
 6. The object detecting method according to claim 1, wherein the selecting of the standard pattern representative point includes setting, as the standard pattern representative point, a standard pattern pixel position that is selected in advance based on design data of the standard pattern without processing actual image information.
 7. The object detecting method according to claim 1, wherein each of the standard pattern and the determined pattern includes an alignment mark used for positioning of a semiconductor wafer.
 8. A non-transitory computer-readable recording medium storing a program that causes a computer to perform the object detecting method according to claim
 1. 